The invention relates to an apparatus for duplicating of film patterns on diazo-material by means of ammonia gas.
Our copending application Ser. No. 830,819 describes a developing apparatus of this type in its basic structure. In such a developing apparatus copies of duplicates are made from a suitable original such as a silver film or a diazo-film onto a further diazo-film by circulating the ammonia gas in a closed, evacuated circuit including the developing chamber. The ammonia gas is compressed in the developing chamber and expanded again as it is returned to a heatable supply chamber. The apparatus includes a closed circuit arrangement between the supply chamber and the developing chamber as well as an evacuating device connected to the developing chamber.
In the parent case and in the references cited in the parent case there is room for improvement, particularly with regard to the construction and control of the membrane pumps and of the structural components essential for the ammonia circulatory system. It is also required for an efficient developing operation, that a specific sequence of steps be rigidly enforced with unfailing repeatability.